Mounting for abrasive wheels



G. W. PERKS MOUNTING FOR ABRASIVE WHEELS Filed Dec. 8 1925 INVENTOR.- 62am: MPI/P/a ATTORNE :Elk 0 Z w C m a My B. a G, G H 6 proved mounting;

Patented Sept. 14, 1926.

UNITED STATES PATENT OFFICE.

- GEORGE w. PEBKB, 0F AKRON, OHIO, ASSIGNOB, BY DIRECT AND MESNE ASSIGN- MENTS, TO THE GEORGE W. PERKS COMPANY, 01 AKRON, OHIO, A CORPORATION OF OHIO.

MOUNTING FOR ABRASIVE WHEELS.

Application filed December 8, 1925. Serial'li'o. 73,996.

The invention relates to mountings for wheels used in grinding operations which rotate at a high rate of s eed and aims to provide means which wil prevent broken parts from being thrown radially outward in the event of wheel breakage so as to lessen the hazard of persons in the vicinity of the wheel.

Heretofore it has been the practice to insert washers of comparatively soft material, such as rubber, leather, lead, blotting paper and the like between the wheel and the clamping collar or flange suitably secured to the revolving shaft forming the supporting spindle for the abrasive Wheel.

The intended function of the washers of rubber, leather and the like formerly used was to prevent fragments of a broken abrasive wheel from being thrown outwardlyvby centrifugal force, but they have been unsatisfactory in practical operation and have frequently caused either death or serious injury to operators or others in the vicinity of a bursting wheel.

My improved means for gripping the abrasive wheel exerts a more tenacious {grip on the latter than the washers of yiel ing material heretofore used and suggested by certain patents in the prior art, and by actual test I have determined that where for mer holding means failed at a given rate of speed, my improved holding means do not so fail.

The characteristic features of my invention will be ap arent from the followin specifications w en read in connection wit the accompanying drawings and points of novelty will be indicated with particularity in the appended claims.

In the drawings:

Figure 1 is a section illustrating an abrasive wheel firmly held in place by my im- F1gure 2 is an end elevation thereof;

Fi ring t e manner in which the comparatively rough surface of the abrasive, wheel interlocks with the film ofyielding material secured to my improved gripping'member';

Figure 4 is a detailed face view of one I of my gripping members;

F1gures'5 and Gare diagrams illustrating the adva'ntage'of a thin film of rubber over thedcomparatively thick washers heretofore us re 3 is a magnified section illustrat- Figure 7 is a cross-section through an abrasive wheel of a somewhat different type shpiwmg the invention as applied thereto; an

Figure 8 is a side view of a clam ing ring used in the construction shown in igure 7.

In these various figures, 10 is any suitable shaft, arranged to revolve an abrasive wheel 11. Shaft 10 has a collar 12 secured thereon in any usual manner in engagement with a shoulder 13 on the shaft. The abrasive wheel 11 is clamped between clamping plates 14 14 by means of a nut, 10 threaded on the end of shaft 10. Each of the clamping plates or flanges 14 is provided with a circular recess or depression 15 below the plane of the flange at its outer diameter, thus providing a raised annular surface 16 which is ressed against the wheel over an area whic may be predetermined.

The gripping members of the present invention are interposed between the flanges 14, 14 and the opposite sides of the abrasive wheeL. They are indicated at 17, 17 and in the form shown each includes a stiff backing plate 18, preferably of metal, having securel vulcanized or otherwise intimately secure thereto a film 19 of tough, yielding rubllnier, such, for example, as tire tread stoc By reference toFigure 3, it will appear that the projections 11 on the sides of the abrasive wheel 11 engage in the rubber surfaces 19 of the members 17, 17 and that the rubber, under the pressure applied by tightening' the clamping nut 10, will be imbedded into the depressions of the wheel 11, the members and wheel thus making an' 1ntimate contact with each other throughout the area of the annular surface 16 of flange 14. It is evident, therefore, that should the abra slve wheel break in use, the centrifugal force exerted by the rapidlyv rotating fragments would be opposed by the grip exerted thereon by the rubber surfaces 19, 19, which, in t rn, would transmit the opposing force to t e metal discs 18, 18, which are made sufiiciently heavy to withstand the centrifugal stresses with an ample factor of safety.

By an exhaustive seriesof experiments, I have found that a comparatively thick layer of rubber'is less effective for the purposes of my'invention than a layer approximately .010 inch in thickness; that due to the. enormous adhesive strength of the rubher when vulcanized to the disc, broken.

fragments of wheels maybe revolved at speeds far in excess of the speed at which similar fragments will fly out when clamped between washers of rubber, blotting paper, or the like, heretofore proposed.

Referring to Figures 5 and 6, the former .figure illustrates a comparatively thick failure is that the longfibers indicated diaclamping member 14 to the shaft 10 which iswell capable of resisting the same. Hence, I

grammatically as f, provide a comparatively long moment arm, indicated by the dimension 0:. Centrifugal force acting in the direction indicated by the arrow P tends to flex the fibers as indicated. This flexing of the fibers reduces the thickness of the washer an amount, for example, as indicated at m (exaggerated) and thus loosens the hold between the flange and wheel and permits fragments to fly outward. In contradistinction, Figure 6 illustrates the gripping member of my invention, in which the film of rubber is of minute thickness, in practice ranging from between .005-to .020 in thickness. The moment arm 02 is practically infinitesimal and there is no decrease in thickness as compared with the decrease marked at m in Figure :5 because the short fibers of the rubber filmi, being comparable to the interstices in the face of the wheel, are in firm I interlocking engagement therewith. Furthermore, my 'film of rubber, being intimately bonded to the metallic disc, 18, will transmit any outwardly acting forces exerted by broken fragments directly to the metal disc. It will be understood that the disc 18 will in turn transmit such force through its own body and through the my improved holding member will prevent a fragment flying from the wheel Where former expedients have failed. Stated in another way, the gripping member embodied in may invention provided with an extremely thin film of rubber 'or the like intimately bonded thereto is capable of exerting a much more tenacious grip on the abrasive .wheel than arrangements heretofore proposed.

In the form of the invention illustrated in Figures 7 and 8, the abrasive wheel is indicated by the numeral 20, being provided about its inner circumference with a rib 2'1.

- The shaftis indicated at 22 and its provided with a flange 23 permanently secured thereto. The wheel is clamped in position between the flange 23 and a removable flange '24, the parts being tightened by bolts 25. In this'form of the invention, the discs are. substantially ring shaped, as indicated at 26,

and are provided with thef facing of rubber 27 as inthe other form of the invention. It

will be notedzthat there is no fit between'the to the disc 01 backing by any suitable mea The thickness of the-layer or film may be varied within narrow limits as indicated. The thickness of the rubber is comparable to the average depth of'the minute interstices in the face of the grinding wheel so that when the pressure is applied, the high points upon the wheel project into the yielding sur* face of the rubberuntil they substantially contact the backing member. In this. way the small acreas of rubber are substantially isolated one from the other and no oppor tunity is afforded for the rubber to creep or work under centrifugal force, and the only way that a fragment can fly out is by tearing the rubber from the disc as hasbeen proven by actual demonstration. The intimate bonding of the rubber film and the disc prevents this action. The surface of the rubber facing is'preferably smooth so that the gripping action will be continuous throughout the extent of the contact between the disc and clamping plate. 4

It will also be noted that the formation of the comparatively narrow annular surfaces 16 about the outer peripheries of the clamp-" ing members 14 concentrates the force which is applied by securi the discs together through tightening oft e nut 10*, over relatively narrow bands. spaced from the center of the grinding wheel, the location of which depends upon the diameter. 'of the flanges 14. In thisinanner the clamping action is concentrated on the outer periphery of the discs and should breakage occur, the ability to retain the broken fragments will. be far superior to a construction in which. the clamps ingforce is distributed throughout the entire area of the disc or near its axis.

It will also be noted'that the rubber facings on the disc have sufficient cushioning properties to compensate for irregularities in the surfaces of the wheel, so that no ex cessive clamping strain can be applied which otherwise would subject the wheel to strains which might. cause its fracture when in serving strain is relieved and may be used re-' peatedly and for clamping wheels of'various grams.

' It is not necessary to have a close fit between thedisc and the shaft, the hole within the center of the disc beingof any desired diameter, as shown, for example, in Figures-,

7 and 8.

gripping member having a thinfilm of rub be'r vulcanized thereto, it'is to be undo stood that I may secure the film of rub.

While I have described quite a mounting for abrasive wheels including-a ties.

I so that the rubber is intimately bonded to the disc. Should other materials than rubher be found to possess suitable properties, I am at liberty to substitute such materials within the scope of the invention. It will also be understood that the principles of the invention may be applied to the clamping of other objects than abrasive wheels, which have surfaces with minute irregulari- While I have described quite. specifically the embodiment of the invention herein illustrated, it is not to be construed that I am limited thereto, as various modifications and substitution of equivalents may be made by those skilled in the art without departure from the invention as defined in the appended claims.

What I claim is:

1. A mounting for abrasive wheels in cluding a rotary shaft and means for c'lamping the Wheel .to said shaft including a pair of clamping elements each having relatively stiff gripping members with a film of yielding, tough rubber vulcanized thereon, the thickness of the film being comparable to the depth of the interstices of the surface of the wheel.

2. A grippingelement for use in mounting abrasive wheels having a rubber fihn forming part thereof of a thickness comparable with the coarseness of the surface of the wheel.

3. A gripping element for use in mount-- ing abrasive wheels, said element including a stiff backing member having secured thereto a film of yielding, tough rubber of a thickness substantially .005 to .020.

4. An abrasive wheel mounting comprising a shaft, an abrasive wheel u on the shaft, a metallic member, a layer rubber permanently secured and bonded to the member adjacent to the Wheel, and means to exert pressure u on said member to force the whee and the ayer of rubber together, the said layer being of such-thickness that when pressure is applied, the high points .upon the wheel will substantially contact the face of the member.

5. An abrasive wheel mounting comprising a shaft, an abrasive wheel upon the shaft, a metallic member, a layer of rubber -permanently secured and bonded to the member adjacent to the wheel, and means to exert pressure upon said member, about a narrow band located near the periphery of the member to force the wheel and the layer of rubber together, the said layer being of such thickness that when pressure is a plied, the high points upon the ,wheel Wlll substantially contact the face of the member.

6. A device of the character described comprising rigid discs, a shaft, an abrasive wheel upon the shaft, means to' exert clamping pressure upon said discsover narrow bands located near the periphery of the discs, and a thin film of yielding material permanently united to each disc adjacent the Wheel, the films of material gripping the rough faces of the wheel and transmitting the centrifugal stresses due to rapid r0- tation of the wheel directly thence to the shaft.

7. A device for clamping an object having minute irregularities in a surface comprising a rigid disk, a layer of rubber intito the discs and mately bonded to said disk, the thickness A of the rubber being commensurate with the depth of said irregularities, and-means for clamping the disk and the object together..

with the layer of rubber in contact with the irregular surface of the object so that the high points in the surface of the object will substantially contact with the face of the disk.

GEORGE W. PERKS. 

